Method for producing a stator and stator for an electric machine

Abstract

The invention relates to a method for producing a stator (1) of an electric machine (2), having a plurality of circumferentially distributed stator slots (3) that extend axially through the stator (1), in each of which a plurality of winding conductors (4) of a shaft winding (5) are arranged and the shaft winding (5) extends axially out of the stator slots (3), forming winding heads (6, 7), wherein the winding conductors (4) have a substantially round conductor cross-section (8) in the region of the winding heads (6, 7) and a conductor cross-section (9) that deviates from the round shape, in particular a substantially angular conductor cross-section (9), in the region of the stator slots (3).

Description

[0001] Method for manufacturing a stator and stator for an electric machine

[0002] The present invention relates to a method for manufacturing a stator and a stator of an electrical machine with a plurality of circumferentially distributed stator slots extending axially through the stator, in each of which a plurality of winding conductors of a wave winding is arranged and wherein the wave winding extends axially out of the stator slots, forming winding heads.

[0003] In modern processes for manufacturing stators with wave windings, it is common to use flat wire, which is wound around a winding blade during the winding process. This process creates a so-called winding mat, which is then inserted into the stator. During flat wire wave winding, twisting of the wire at the outermost point of the winding blade is inevitable. This twisting causes the wire, particularly in the area of ​​the winding ends, to remain in a twisted state after the winding process.

[0004] To reduce the excessive height of the winding heads, the winding mat is compressed in a forming station after winding. While this compression can reduce the height of the winding heads to some extent, the wire remains twisted in the winding head area. This results in the winding heads remaining too large in diameter and too tall, often causing problems with installation space constraints, for example, within electrically powered vehicles. The excessive space required by the winding heads makes it difficult to integrate the stator into compact machines and reduces design flexibility.

[0005] Another problem is that further reducing the winding head height by more intensively compressing the winding mat is currently hardly possible without damaging the copper wire insulation. Compressing the twisted flat wire results in high mechanical stress on the insulation, significantly increasing the risk of damage. Such insulation damage can lead to electrical short circuits or failures of the electrical machine, thus compromising the machine's reliability.

[0006] It is therefore the object of the invention to provide a method for manufacturing a stator and a correspondingly designed stator with which lower axial heights of the winding heads can also be made possible without reducing the electrical power of the electric machine.

[0007] This problem is solved by a method for manufacturing a stator of an electrical machine according to claim 1 and a stator of an electrical machine according to claim 7.

[0008] By using winding conductors with a round, particularly circular and / or oval, cross-section in the winding heads and a cross-section that deviates from the round shape in the stator slots, the winding heads can be designed more compactly, saving space and improving axial space utilization in the stator. At the same time, the cross-section in the slots, adapted to flat wire, ensures optimal space utilization and thus improved heat dissipation, resulting in more consistent electrical performance. The round cross-section in the winding heads reduces mechanical stresses and minimizes the risk of insulation damage, increasing the service life and reliability of the electric machine. Overall, this combination leads to a more efficient and cost-effective machine design.

[0009] The use of round wire instead of flat wire as the starting material for the wave winding offers further advantages. Round wire is more cost-effective to procure, as it is significantly cheaper than flat wire, which considerably reduces material costs. Furthermore, the round cross-section allows for improved cooling of the winding conductors, particularly in the winding ends, because heat is dissipated more efficiently. This leads to higher performance of the electric machine, as the windings can be subjected to greater loads without overheating. First, the individual elements of the claimed invention are explained in the order they appear in the claim set, and subsequently, particularly preferred embodiments of the invention are described.

[0010] stator

[0011] For the purposes of this patent application, a stator is a stationary, immobile component of an electric machine whose function is to generate or conduct the magnetic field that interacts with the rotor of the machine. The stator thus forms the stationary component of the machine, while the rotor is the rotating component. In electric machines, the stator is of central importance because it either receives the magnetic flux of the rotor or generates the electromagnetic field required for the operation of the machine.

[0012] The stator is preferably constructed with a plurality of axially extending stator slots in which winding conductors are arranged. These winding conductors are configured as wave windings that extend from the slots at the ends of the stator through winding heads. The stator is advantageously made of a magnetically conductive material that efficiently conducts the magnetic flux lines while simultaneously offering high mechanical stability. Insulation is advantageously used between the slots and the winding conductors to prevent electrical short circuits and ensure operational reliability.

[0013] Several stator designs are conceivable. In a preferred embodiment, the stator consists of a laminated core, which reduces eddy current losses and thus increases machine efficiency. Another conceivable embodiment may involve the use of stators with integrated cooling channels, which enable improved heat dissipation and thus allow for higher power outputs. The stator can also have different geometric shapes, depending on the specific machine application. For example, it may have a cylindrical shape in compact machines, while segmented or modular stators are preferred for other applications, as they facilitate easier assembly and maintenance.

[0014] Stator slots

[0015] For the purposes of this patent application, a stator groove is an elongated recess extending axially along the circumference of the stator of an electrical machine and serving to accommodate winding conductors. Stator grooves are integral components of the stator and have the essential function of receiving, guiding, and mechanically stabilizing the winding conductors of the shaft winding.

[0016] The slots can have various cross-sectional shapes to meet the specific requirements of the winding and the electric machine. Preferably, the geometry of the stator slots is designed to allow the largest possible contact area with the winding conductors to ensure effective heat dissipation. One possible embodiment is a rectangular or trapezoidal cross-sectional shape, which allows for dense packing of the winding conductors while simultaneously promoting mechanical stability. Another conceivable embodiment is a slightly curved slot geometry, which is particularly advantageous when optimal force distribution on the winding conductors is desired. It is also possible for the slots to have different depths, depending on the specific requirements of the winding and the electric machine.In some cases, the stator slots may have additional coatings or special materials to improve electrical insulation or optimize heat dissipation.

[0017]

[0018] For the purposes of this patent application, a winding conductor is an electrical conductor used in an electric machine to form the windings and to conduct electric currents in order to generate a magnetic field or to be embedded in a magnetic field. Winding conductors consist of a conductive material, preferably copper or aluminum, which has high electrical conductivity and enables efficient current transmission. The winding conductors are positioned in the stator slots of a stator and, together with the winding heads formed at the axial ends of the stator slots, constitute the wave winding of the electric machine.

[0019] In preferred embodiments, winding conductors have a round and a square cross-section. The round, in particular circular and / or oval, cross-section is advantageously used in the area of ​​the winding heads, as it reduces the mechanical stress during the winding process and protects the insulation. In the area of ​​the stator slots, a square, in particular a substantially rectangular, cross-section is preferably used to ensure optimal space utilization and improve heat dissipation.

[0020] The winding conductors can be made of solid copper or aluminum to ensure high electrical conductivity. Alternatively, the winding conductors can be hollow to reduce weight and improve heat dissipation. Another possible design involves the insulation of the winding conductors. This can consist of a thermally resistant plastic coating or be implemented as lacquered copper or aluminum conductors to achieve high insulation strength. Designs with special coatings that increase thermal or mechanical resistance are also possible.

[0021]

[0022] For the purposes of this patent application, a wave winding is a specific type of winding in which the winding conductors are arranged around the stator in such a way that they extend axially through the stator slots in a wave-like structure.

[0023] The wave winding is preferably supplied as a pre-formed winding mat, which is inserted into the stator slots. This winding mat is manufactured outside the stator on a winding blade by winding the winding conductors into a flat structure. The winding mat is then transferred to the stator slots and further processed there. This method allows the winding conductors to be inserted precisely into the stator slots, increasing the efficiency of the manufacturing process and ensuring uniform placement of the winding conductors within the stator.

[0024] The function of the wave winding is to optimize electromagnetic power transmission in the electric machine. The wave-like arrangement of the winding conductors enables a uniform distribution of the magnetic flux in the stator, leading to improved efficiency and performance of the machine. The winding mat, as an intermediate product, also facilitates the installation of the winding in the stator, since the winding conductors are already pre-formed and, thanks to the compact design of the winding heads, make optimal use of the available installation space both axially and radially.

[0025] Advantageously, the winding conductors in the area of ​​the winding heads are designed with a circular cross-section, while in the area of ​​the stator slots they are deformed to an essentially square or rectangular cross-section in order to achieve a higher packing density and better heat dissipation.

[0026] Advantageous embodiments of the invention

[0027] According to an advantageous embodiment of the invention, the conductor cross-section, which deviates from a circular shape, in the area of ​​the stator slots can be designed such that the winding conductors make essentially flat contact with the side walls of the stator slots. Advantageously, the flat contact of the winding conductors with the side walls of the stator slots enables improved mechanical stability of the winding, because the flat contact effectively allows the winding conductors to be braced between the slot walls and also between themselves. This ensures a more even load distribution and reduces mechanical vibrations during operation. Furthermore, the flat contact improves heat dissipation from the winding conductors into the stator, which reduces the operating temperature of the machine and extends its service life.The precise adaptation of the winding conductors to the slots also leads to more efficient manufacturing and minimizes material usage.

[0028] Integrating a stator designed according to the invention into an electric machine offers the advantage of a more compact and efficient overall machine. The improved space utilization achieved through the optimized stator allows for higher power density, leading to increased efficiency. Simultaneously, the more robust and precise winding geometry results in enhanced operational reliability due to reduced mechanical and thermal stresses. Furthermore, the use of round wire, which is less expensive than flat wire, reduces material costs, improving the overall economic viability of the machine. Thanks to improved cooling of the winding conductors, the machine can deliver higher power output because heat dissipation is more effective and higher currents can flow.Finally, the electrical wiring is simplified by the easy connection of the winding conductors to a high-voltage terminal, which reduces assembly effort and increases the machine's reliability. Furthermore, the installation space in the stator is optimally utilized, enabling a more compact machine design and increasing its efficiency.

[0029] The object of the invention is particularly achieved by a method for manufacturing a stator with a wave winding, comprising the following steps:

[0030] a) Provision of a plurality of winding conductors with a round conductor cross-section;

[0031] b) Winding a winding blade with the winding conductors to form a wave winding, whereby the round conductor cross-section of the winding conductors is maintained;

[0032] c) Transfer of the wave winding into a linear magazine;

[0033] d) Plastic pre-shaping of the winding conductors in the areas that are to be inserted into the stator slots of the stator, so that they have a conductor cross-section that deviates from the round shape in these areas;

[0034] e) Rolling the wave winding into a drawing mandrel;

[0035] f) Expanding the wave winding from the insertion mandrel into the stator slots of the stator;

[0036] g) Plastic deformation of the areas of the winding conductors inserted in the stator slots by means of a tool that exerts a force directed radially to the base of a stator slot on the corresponding winding conductors, so that the winding conductors assume a substantially rectangular conductor cross-section.

[0037] Using a stator manufacturing process with circular winding conductors as the starting material offers the advantage of allowing for more compact winding heads without damaging the insulation. This significantly reduces the height and diameter of the winding heads, resulting in a space-saving design. This facilitates the integration of the electrical machine into applications with limited installation space and minimizes the risk of insulation damage during manufacturing. The more compact winding heads also contribute to improved thermal properties and overall machine efficiency.

[0038] The stator manufacturing process offers further advantages. Using round wire is not only more cost-effective than flat wire, but also allows for better cooling of the winding conductors, as the round cross-section ensures improved heat dissipation. This leads to higher stator performance, since the windings can operate more efficiently. Finally, the design facilitates simple and safe connection of the winding conductors to a high-voltage terminal, which reduces assembly time and makes the electrical connection more reliable. This combination of cost savings, increased performance, and process simplification makes the process particularly economical and efficient.

[0039] According to a further particularly preferred embodiment of the invention, it can be provided that, after process step c), and especially before and / or after process step d), and / or simultaneously, the winding conductors in the area of ​​the winding heads are deformed. Furthermore, the invention can also be further developed such that the deformation of the winding conductors in the area of ​​the winding heads is carried out by means of a force directed axially towards the stator. The targeted deformation of the winding conductors in the area of ​​the winding heads by an axially directed force offers the advantage that the winding heads can be reduced to a defined height without damaging the insulation of the conductors. This results in winding conductor sections with substantially circular and those with substantially oval cross-sections in the area of ​​the winding heads.

[0040] In a further preferred embodiment of the invention, the compression of the winding conductors in the stator slots can also be carried out in such a way that the conductor cross-sections are adapted to the geometry of the stator slots, which offers the advantage of optimal space utilization and packing density. This improves both the mechanical stability and the heat dissipation of the windings. At the same time, the risk of air gaps is reduced, leading to higher efficiency and improved thermal performance of the electric machine.

[0041] It can also be advantageous to further develop the invention such that the crimping of the winding conductors in the stator slots is carried out in such a way that, after crimping, the conductor cross-sections bear against the side walls of the stator slots, at least partially. By making full contact of the winding conductors against the side walls of the stator slots, heat dissipation is maximized, leading to more effective cooling of the windings. The rectangular conductor cross-sections resulting from plastic deformation in the stator slots, which thus also adapt to the geometry of the stator slots, further increase mechanical stability and reduce the risk of vibrations and material fatigue. Depending on the degree of deformation, winding conductor cross-sections are formed in the stator slots that closely resemble the flat wire waveguides that are predominantly rectangular and preferably used today.

[0042] According to a further preferred embodiment of the invention, the plastic deformation and thus the compression of the winding conductors in the stator slots can be carried out in several stages. Multi-stage compression of the winding conductors offers the advantage that the deformation process is controlled and carried out stepwise, which increases accuracy and minimizes the risk of insulation damage. Thus, a round wire can be deformed even more precisely into a flat wire with its special properties within the stator slots.

[0043] The invention will now be explained in more detail with reference to figures, without limiting the general concept of the invention.

[0044] It shows:

[0045] Figure 1 shows an electric machine in a schematic axial sectional view.

[0046] Figure 2 shows a cross-sectional view through the stator of the electric machine,

[0047] Figure 3 shows a cross-sectional view through the winding head of the stator,

[0048] Figure 4 shows a schematic representation of a manufacturing process for a stator.

[0049] Figure 1 shows a stator 1 of an electric machine 2 with a plurality of circumferentially distributed stator slots 3 extending axially through the stator 1, in each of which a plurality of winding conductors 4 of a wave winding 5 is arranged and the wave winding 5 extends axially out of the stator slots 3 forming winding heads 6,7.

[0050] As can be seen from Figures 2 and 3, the winding conductors 4 have a substantially circular conductor cross-section 8 in the area of ​​the winding heads 6, 7 and a conductor cross-section 9 that deviates from the circular shape, in particular a substantially rectangular conductor cross-section 9, in the area of ​​the stator slots 3. The conductor cross-section 9 that deviates from the circular shape is designed in the area of ​​the stator slots 3 such that the winding conductors 4 make substantially flat contact with the side walls 13 of the stator slots 3. The stator 1 shown in Figures 1-3 can be manufactured as follows, as sketched in Figure 4. First, in a first step, a) a plurality of winding conductors 4 with a substantially circular conductor cross-section 8 are provided.Next, a winding blade is wound with the winding conductors 4 to form a wave winding 5, whereby the substantially circular conductor cross-section 8 of the winding conductors 4 is maintained. This wave winding 5 is then transferred to a linear magazine 10. This state of the filled linear magazine 10 can be seen in process step c) in Figure 4.

[0051] In the linear magazine 10, a first plastic pre-shaping of the winding conductors 4 is carried out by means of a tool 14 in the areas that are to be inserted into the stator slots 3 of the stator 1, so that they have a conductor cross-section 9' that deviates from a circular shape in these areas. Before and / or after this process step and / or simultaneously, the winding conductors 4 can also be deformed in the area of ​​the winding heads 6, 7 by deforming the winding conductors 4 in the area of ​​the winding heads 6, 7 by means of a force directed axially towards the stator 1.

[0052] Following this, the wave winding 5 is rolled into a drawing mandrel 11 and the wave winding 5 is expanded from the drawing mandrel 11 into the stator slots 3 of the stator 1, which is sketched in figure f) of figure 4.

[0053] A second plastic deformation of the sections of the winding conductors 4 inserted in the stator slots 3 is now carried out using a tool 12. This tool exerts a force on the respective winding conductors 4, directed radially towards the base 13 of a stator slot 3, so that the winding conductors assume a conductor cross-section that deviates from a circular shape, in particular a substantially rectangular conductor cross-section 9". The pressing of the winding conductors 4 in the stator slots 3 is carried out in such a way that the conductor cross-sections 9" are adapted to the geometry of the stator slots 3 and that, after pressing, the conductor cross-sections 9" bear against the side walls 13 of the stator slots 3, at least partially.

[0054] Figure 4 is explained in more detail below. Figure 4 schematically shows the multi-stage forming and insertion process of a wave winding 5 into the stator slots 3 of a stator 1. The wave winding 5, which consists of several round wires, is transferred to a linear magazine 10 after the winding process. Each slot of the linear magazine 10 contains two winding conductors 4 (round wires) of the wave winding 5. In the forming process shown, the winding heads 6, 7 of the wave winding 5 are first compressed. These winding heads 6, 7 are compressed, if necessary, to the maximum permissible height to ensure that they are suitable for the subsequent processing steps. The shape of the winding heads 6, 7 is not important; what is crucial is that the insulation of the winding conductors 4 remains undamaged during the compression process.

[0055] After the winding heads 6, 7 have been machined, the "straight section" of the shaft winding 5 is also pre-formed. The "straight section" of the shaft winding 5 refers to the portion where the winding conductors 4 of the shaft winding 5 run within the stator slots 3 of the stator 1. This section differs from the winding heads 6, 7, which are located at the axial ends of the winding and protrude from the stator slots 3. In the straight section, the winding conductors 4 run parallel to the longitudinal axis of the stator 1 within the stator slots 3 and are securely embedded there.

[0056] In this step, the two round wires per stator slot 3 are deformed to such an extent that they can easily fit into the slots of the insertion mandrel 11 and be centered during the subsequent rolling process. While more extensive pre-forming in the linear magazine 10 would be possible, it is necessary that the winding conductors 4 (round wires) can still be pushed out of the slots of the linear magazine 10 without damaging the insulation of the winding conductors 4.

[0057] After pre-forming, the wave winding 5 is transferred into the insertion mandrel 11. This step is also shown in Figure 4, where the insertion mandrel 11 receives the winding conductors 4 (round wires) in the stator slots 3. The round wire makes it easier and safer to transfer the wave winding 5 into the slots of the insertion mandrel 11, thereby significantly reducing the risk of damage to the insulation.

[0058] In the next step, expansion, the wave winding 5 is expanded from the insertion mandrel 11 into the stator 1. The nearly round cross-section of the round wires ensures that the risk of insulation damage is minimized in this process step as well. Once the wave winding 5 has been expanded into the stator 1, the second part of the forming process begins, in which the already pre-formed round wires are further compressed to achieve the required nominal dimension. This is done either simultaneously or in stages with a tool 12 that exerts a force radially directed towards the bottom of the slot on the winding conductors 4. The final deformation of the winding conductors 4 in the stator slots 3 helps to reduce the cavities in the stator slots 3, which enables improved heat dissipation. In addition, this increased compression reduces the need for trickle resin, as there is less space available for the trickle application process.

[0059] In summary, the invention offers the following advantages in particular:

[0060] - When winding the winding bar: The round wire retains its original shape when wrapped around the winding bar and therefore lies more securely against it. A rectangular wire is more likely to twist at the wrap, becoming wider and taller, which results in a diagonal stretch of the flat wire. Furthermore, the cross-section of the round wire remains round in the area of ​​the winding heads despite twisting. This results in a lower mat height, and the area that needs to be pressed (shaped) is always round and therefore has no sharp edges like those of flat wire.

[0061] - When rolling and expanding the winding mat: Transferring the round wire winding mat from the linear magazine into the grooves of the rolling mandrel is significantly easier, as its width does not change during twisting. The twisted flat wire is wider (diagonal length), which makes transfer considerably more difficult and can lead to insulation damage. - When pressing or forming the winding mat in the stator grooves, steel tools can be used. Plastic tools are used for flat wire, as otherwise the insulation will be damaged. The round wire winding mat can be pressed (formed) much more tightly without damaging the insulation.

[0062] - When using round wires in general: Round wires can be mechanically stripped at the wire ends, which are not deformed according to the invention. This is more cost-effective and also produces less mess. Square flat wires, on the other hand, are more laboriously stripped using a laser. Furthermore, round wires are easier to process as a starting material and can also be compacted more effectively, especially in the winding head areas.

[0063] The combination of round wire and flat wire cross-sections according to the invention thus makes it possible to ideally combine the positive properties of both cross-sections in a wave winding and thus to optimize the efficiency of the electric machine. (List of reference symbols)

[0064] 1 Stator

[0065] 2 electric machine

[0066] 3 stator slots

[0067] 4 winding conductors

[0068] 5 wave winding

[0069] 6 winding head

[0070] 7 winding head

[0071] 8 round conductor cross-section

[0072] 9' different conductor cross-section

[0073] 9" essentially rectangular conductor cross-section

[0074] 10 linear magazine

[0075] 11 Draw-in mandrel

[0076] 12 tools

[0077] 13 side walls

[0078] 14 tools

Claims

Claims 1. Method for manufacturing a stator (1 ) with a wave winding (5), comprising the following steps: h) Provision of a plurality of winding conductors (4) with a round conductor cross-section (8); i) Winding a winding blade with the winding conductors (4) to form a wave winding (5), whereby the round conductor cross-section (8) of the winding conductors (4) is retained; j) Transfer of the wave winding (5) into a linear magazine (10); k) Plastic pre-shaping of the winding conductors (4) in the areas which are to be inserted into the stator slots (3) of the stator (1), so that in these areas they have a conductor cross-section (9') which deviates from the round shape; l) Rolling the wave winding (5) into a drawing mandrel (11 ); m) Expanding the wave winding (5) from the insertion mandrel (11) into the stator slots (3) of the stator (1); n) Plastic deformation of the areas of the winding conductors (4) inserted in the stator slots (3) by means of a tool (12) which exerts a force directed radially to the base of the slot (13) of a stator slot (3) on the corresponding winding conductors (4) so ​​that the winding conductors assume a substantially rectangular conductor cross-section (9").

2. Method according to claim 1 , characterized in that the winding conductor (4) is deformed in the area of ​​the winding heads (6,7) after process step c).

3. Method according to claim 2, characterized by the fact that the deformation of the winding conductors (4) in the area of ​​the winding heads (6,7) is carried out by means of a force directed axially towards the stator (1).

4. Method according to any one of claims 1 to 3, characterized by the fact that the second plastic deformation of the winding conductors (4) in the stator slots (3) is carried out in such a way that the resulting conductor cross-sections (9") are adapted to the geometry of the stator slots (3).

5. Method according to any of the preceding claims, characterized by the fact that the second plastic deformation of the winding conductors (4) in the stator slots (3) is carried out in such a way that, after the compression caused thereby, the conductor cross-sections (9") are at least partially in contact with the side walls (13) of the stator slots (3).

6. Method according to any of the preceding claims, characterized by the fact that The plastic deformation of the winding conductors (4) in the stator slots (3) is carried out in several intermediate stages.

7. Stator (1 ) of an electrical machine (2) with a plurality of circumferentially distributed stator slots (3) extending axially through the stator (1), in each of which a plurality of winding conductors (4) of a wave winding (5) is arranged and wherein the wave winding (5) extends axially out of the stator slots (3) forming winding heads (6,7), characterized in that the winding conductors (4) in the area of ​​the winding heads (6,7) have round, in particular circular and oval, conductor cross-sections and in the area of ​​the stator slots (3) have a substantially rectangular conductor cross-section (9").

8. Stator according to claim 7, characterized by the fact that the essentially rectangular conductor cross-section (9") of the winding conductor (4) in the area of ​​the stator slots (3) is designed such that the conductor cross-sections (9") are at least partially in contact with the side walls (13) of the stator slots (3).

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